Traveling vehicle controller and traveling vehicle system

ABSTRACT

A traveling vehicle controller includes a command assignment controller to detect a first-to-arrive traveling vehicle that is able to reach a destination point first among traveling vehicles, based on travel route candidates on which the traveling vehicles travel along a travel path from respective positions to reach the destination point, and assign the command to the first-to-arrive traveling vehicle. During detection of the first-to-arrive traveling vehicle, when a traveling vehicle traveling toward a branch point on the travel path is located within a range of a branch-switching impossible distance from the branch point and is scheduled to proceed toward a main way at the branch point, the command assignment controller performs pseudo-shift processing by which this traveling vehicle is determined to be located in a position downstream of the branch point and on a side of the main way.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a traveling vehicle controller and atraveling vehicle system.

2. Description of the Related Art

Conventionally, a traveling vehicle controller configured to assign, toany one of a plurality of traveling vehicles each configured to travelon a travel path including branch points, a command to travel to adestination point on the travel path has been known (see Japanese PatentNo. 5278736, for example). In this traveling vehicle controller, thecommand is commonly assigned to a traveling vehicle that is closest tothe destination point.

In the above-described traveling vehicle controller, when the command isassigned to a traveling vehicle that is approaching a branch point onthe travel path, the traveling vehicle may fail to change courses towardthe destination point at the branch point, and may detour to traveltoward the destination point. Consequently, arrival of the travelingvehicle at the destination point may be late.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide traveling vehiclecontrollers and traveling vehicle systems that each enable a travelingvehicle to quickly reach a destination point.

A traveling vehicle controller according to a preferred embodiment ofthe present invention is a traveling vehicle controller to assign, toany one of a plurality of traveling vehicles that each travels on atravel path including a branch point, a command to travel to adestination point on the travel path. The traveling vehicle controllerincludes a command assignment controller to detect a first-to-arrivetraveling vehicle that is able to reach the destination point firstamong the traveling vehicles, based on travel route candidates on whichthe traveling vehicles travel along the travel path from respectivepositions to reach the destination point, and assign the command to thefirst-to-arrive traveling vehicle. During detection of thefirst-to-arrive traveling vehicle, when one of the traveling vehiclestraveling toward the branch point on the travel path is located within arange of a branch-switching impossible distance from the branch pointand is scheduled to proceed toward a main way at the branch point, thecommand assignment controller performs pseudo-shift processing by whichthe one of the traveling vehicles is considered to be located in aposition downstream of the branch point and on a side of the main way.

When courses of a traveling vehicle that is traveling are changed at thebranch point, in order to switch a branch mechanism, for example, thistraveling vehicle is located apart from the branch point with a distancelonger than the branch-switching impossible distance. Thus, for atraveling vehicle that is traveling toward the branch point on thetravel path and is located within the range of the branch-switchingimpossible distance from the branch point, it is difficult to changecourses toward a branch way at the branch point (i.e., to travel along apost-course-switch travel route), and the traveling vehicle has toproceed toward the main way. Accordingly, by performing the pseudo-shiftprocessing, the traveling vehicle controller determines the travelingvehicle to be located at a position downstream of the branch point andon the side of the main way. Consequently, a travel route on which atraveling vehicle located within the range of the branch-switchingimpossible distance from the branch point and scheduled to travel towardthe main way at the branch point, after this moment as a starting point,proceeds toward the branch way when passing through the branch pointfirst is excluded from the travel route candidates. Thus, a situation inwhich a traveling vehicle to which the command has been assigned is notable to change courses at the branch point and detours to travel to thedestination point is able to be avoided. Accordingly, a travelingvehicle is able to quickly reach the destination point.

In a traveling vehicle controller according to a preferred embodiment ofthe present invention, the command assignment controller may calculate,for each of the travel route candidates, a period of time for eachtraveling vehicle to travel thereon, and may detect, as thefirst-to-arrive traveling vehicle, a traveling vehicle corresponding toa travel route candidate on which the period of time is shortest.Accordingly, the first-to-arrive traveling vehicle is able to beaccurately detected.

In a traveling vehicle controller according to a preferred embodiment ofthe present invention, when having performed the pseudo-shiftprocessing, the command assignment controller may add a period of timeto travel between a pseudo-position of the traveling vehicle subjectedto the pseudo-shift processing and an actual position of the travelingvehicle to the period of time calculated for the travel route candidatecorresponding to the traveling vehicle. By this addition, the period oftime of the travel route candidate of the traveling vehicle subjected tothe pseudo-shift processing is able to be corrected.

In a traveling vehicle controller according to a preferred embodiment ofthe present invention, in the pseudo-shift processing, the travelingvehicle may be determined to be located downstream of the branch pointand within a distance range equal or substantially equal to or shorterthan a vehicle length of the traveling vehicle from the branch point. Ifthe distance between the pseudo-position and the actual position of thetraveling vehicle subjected to the pseudo-shift processing is longer,another traveling vehicle is more likely to exist therebetween. In thiscase, even though the other traveling vehicle is able to reach thedestination point first, the traveling vehicle subjected to thepseudo-shift processing is recognized to be located in thepseudo-position, and thus there is a possibility that the command isassigned to the traveling vehicle subjected to the pseudo-shiftprocessing. Accordingly, in the traveling vehicle controller, becausethe traveling vehicle is determined to be located within the distancerange equal or substantially equal to or shorter than the vehicle lengthof the traveling vehicle from the branch point, there is no possibilitythat another traveling vehicle exists between the pseudo-position andthe actual position of the traveling vehicle subjected to thepseudo-shift processing. Thus, a situation in which the command isassigned to the traveling vehicle subjected to the pseudo-shiftprocessing although the command should be originally assigned to theother traveling vehicle is able to be avoided.

In a traveling vehicle controller according to a preferred embodiment ofthe present invention, the branch-switching impossible distance may beset to increase continuously or stepwise as the vehicle speed of thetraveling vehicle increases. In order to reliably change courses of thetraveling vehicle at the branch point, the branch-switching impossibledistance being upstream from the branch point tends to increase as thevehicle speed of the traveling vehicle increases. Thus, in the travelingvehicle controller according to this aspect of a preferred embodiment ofthe present invention, the branch-switching impossible distance is ableto be set according to this tendency.

A traveling vehicle controller according to a preferred embodiment ofthe present invention is a traveling vehicle controller to assign, toany one of a plurality of traveling vehicles that each travels on atravel path including a branch point, a command to travel to adestination point on the travel path. The traveling vehicle controllerincludes a command assignment controller to detect a first-to-arrivetraveling vehicle that is able to reach the destination point firstamong the traveling vehicles, based on travel route candidates on whichthe traveling vehicles travel along the travel path from respectivepositions to reach the destination point, and assign the command to thefirst-to-arrive traveling vehicle. During detection of thefirst-to-arrive traveling vehicle, in a case when one of the travelingvehicles traveling toward the branch point on the travel path is locatedwithin a range of a branch-switching impossible distance from the branchpoint and is scheduled to travel toward a main way at the branch point,the command assignment controller excludes, from the travel routecandidates, a post-course-switch travel route on which the one of thetraveling vehicles proceeds toward a branch way when passing through thebranch point first after the moment of the case as a starting point.

In the detection of the first-to-arrive traveling vehicle, when thattraveling vehicle is located within the range of the branch-switchingimpossible distance from the branch point, the post-course-switch travelroute is excluded from the travel route candidates. Thus, a situation inwhich a traveling vehicle to which the command has been assigned is notable to change courses at the branch point and detours to travel to thedestination point is able to be avoided. Accordingly, a travelingvehicle is able to quickly reach the destination point.

A traveling vehicle system according to a preferred embodiment of thepresent invention includes a travel path including a branch point, aplurality of traveling vehicles that each travels along the travel path,and one of the traveling vehicle controllers according to variouspreferred embodiments of the present invention described above.

In the traveling vehicle system described above, because it includes oneof the above-described traveling vehicle controllers, a travelingvehicle is able to quickly reach the destination point.

According to the preferred embodiments of the present invention, thetraveling vehicle controllers and the traveling vehicle systems thateach enable an empty traveling vehicle to quickly reach the destinationpoint are able to be provided.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a traveling vehicle system according to apreferred embodiment of the present invention.

FIG. 2 is a block diagram showing features of a traveling vehicle systemaccording to a preferred embodiment of the present invention.

FIG. 3 is a diagram showing pseudo-shift processing according to apreferred embodiment of the present invention.

FIG. 4 is another diagram showing a pseudo-shift processing according toa preferred embodiment of the present invention.

FIG. 5 is a flowchart showing a pseudo-shift processing according to apreferred embodiment of the present invention.

FIG. 6 is a flowchart showing inverse route search processing accordingto a preferred embodiment of the present invention.

FIG. 7A is a diagram showing inverse route search processing accordingto a preferred embodiment of the present invention. FIG. 7B is a diagramshowing a continuation of FIG. 7A.

FIG. 8A is a diagram showing a continuation of FIG. 7B.

FIG. 8B is a diagram showing a continuation of FIG. 8A.

FIG. 9A is a diagram showing a continuation of FIG. 8B.

FIG. 9B is a diagram showing a continuation of FIG. 9A.

FIG. 10A is a diagram showing a continuation of FIG. 9B.

FIG. 10B is a diagram showing a continuation of FIG. 10A.

FIG. 11 is a diagram showing a continuation of FIG. 10B.

FIG. 12 is a flowchart showing inverse route search processing accordingto a modification according to a preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be describedwith reference to the drawings. In description of the drawings, likeelements are designated by like reference signs, and duplicatedescription is omitted. The scale in the drawings does not necessarilycoincide with the size of a described object.

A traveling vehicle system 1 shown in FIG. 1 is a system in which atraveling vehicle 3 travels along a track 2 installed on a ceiling of afactory, for example. The traveling vehicle system 1 defines a transportsystem to convey loads L. The loads L are containers that each stores aplurality of semiconductor wafers, for example, and may be glasssubstrates and general parts, for example. The traveling vehicle system1 mainly includes the track 2, a plurality of the traveling vehicles 3,and a traveling vehicle controller 4.

The track 2 is a predetermined travel path along which the travelingvehicles 3 travel. The track 2 is a one-way travel path. In other words,in the traveling vehicle system 1, as shown by white arrows in FIG. 1,the traveling direction (advancing direction) of each traveling vehicle3 in the track 2 is set to be one direction, and traveling in theopposite direction is prohibited. The track 2 is suspended from theceiling of a factory, for example. The track 2 includes a branch pointBP. The branch point BP is a point at which a branch way is separatedfrom a main way. The branch way corresponds to a traveling direction(course direction) different from that of the main way.

In the example of a track layout shown in FIG. 1, the track 2 includestwo loop travel paths 2A, 2B and two communication travel paths 2C, 2Dthat provide communication between the loop travel paths 2A, 2B fortraveling vehicles 3 to travel between the loop travel paths 2A, 2B. Ata position where the communication travel path 2C is connected to theloop travel path 2A (branches off from the loop travel path 2A) and aposition where the communication travel path 2D is connected to the looptravel path 2B (branches off from the loop travel path 2B), branchpoints BP are provided. At the branch point BP on the loop travel path2A, either one of communication travel path 2C and the loop travel path2A downstream of the branch point BP defines and functions as a mainway, and the other defines and functions as a branch way.

Each traveling vehicle 3 is able to transfer a load L. The travelingvehicle 3 is an overhead traveling automated guided transport vehiclethat travels along the track 2. The traveling vehicle 3 is also called,for example, a carriage (traveling carriage), an overhead travelingvehicle (overhead traveling carriage), or a transport vehicle (transportcarriage). The traveling vehicle 3 includes a position determiner 31, avehicle controller 32, and a branch mechanism 33 as shown in FIG. 2 inaddition to a mechanism to transfer a load L to or from a load port, forexample.

The position determiner 31 determines the position of the travelingvehicle 3 on the track 2. For example, the position determiner 31includes a reader to read a point mark (e.g., bar code) that is attachedin plurality to be aligned at regular intervals along the track 2 and anencoder. The position determiner 31 acquires positional information ofthe traveling vehicle 3 in the track 2. The positional information ofthe traveling vehicle 3 is provided from information of a point markdetermined by the reader and the encoder. This positional informationalso includes information on a travel distance after the travelingvehicle 3 passes through the point mark.

The vehicle controller 32 controls operation of the traveling vehicle 3.The vehicle controller 32 is, for example, an electronic controllerincluding a central processing unit (CPU), a read only memory (ROM), anda random access memory (RAM). The vehicle controller 32 may beimplemented by, for example, software defined by a program that is ableto be stored in the ROM and loaded into the RAM to be executed by theCPU. Herein, the vehicle controller 32 may be implemented by hardware,for example, an electronic circuit.

The vehicle controller 32 controls operation of the traveling vehicle 3based on a transport command received from the traveling vehiclecontroller 4. In the transport command, for example, a loading port thatis a load port on which a load L to be conveyed is placed and anunloading port that is a load port to which the load L is to be conveyedare specified. The vehicle controller 32 causes the traveling vehicle 3to travel to the loading port and load the load L thereon, and thencauses the traveling vehicle 3 travel to the unloading port and unloadthe load L therefrom. The vehicle controller 32 performs park control ofcausing the traveling vehicle 3 to travel to a standby section where thetraveling vehicle 3 is to be put on standby. The vehicle controller 32performs ejection control of causing the traveling vehicle 3 to travelto depart from the standby section. Specific processes for the parkcontrol and the ejection control are not limited to particular ones, andvarious known processes may be implemented.

The branch mechanism 33 is a mechanism to change the traveling directionof the traveling vehicle 3 at a branch point BP. The branch mechanism 33switches a branch lever (not shown) in accordance with the travelingdirection of the traveling vehicle at the branch point BP. Thisswitching occurs over a predetermined period of time.

The traveling vehicle 3 periodically transmits traveling information ona traveling status of the traveling vehicle 3 to the traveling vehiclecontroller 4. The traveling information is information representing astate of the traveling vehicle 3 itself. The traveling informationincludes at least the positional information of the traveling vehicle 3,vehicle speed information of the traveling vehicle 3, information on thepresence or absence of a load L, information on whether the travelingvehicle 3 is traveling (e.g., which is performing the park control orthe ejection control), and, if the traveling vehicle 3 is traveling, atravel schedule route related to a schedule of this traveling (travelplan).

As shown in FIG. 1 and FIG. 2, the traveling vehicle controller 4defines and functions as a host controller for the vehicle controller32. For example, when having received a loading request to acquire aload L in a loading port SP from a manufacturing controller (not shown)or the like, the traveling vehicle controller 4 generates a transportcommand corresponding to this loading request. The loading port SP is aport on which a load L requested to be loaded among a plurality of portsaligned parallel or substantially parallel to each other along the track2. Examples of this port include a load port of a processing device, aloading-and-unloading port of a stocker, and a buffer as a place where aload L is temporarily stored. The loading port SP is also called afrom-port. A method to generate the transport command is not limited toa particular one, and various known methods may be implemented.

The transport command includes at least a command to cause the travelingvehicle 3 to travel to a destination point P corresponding to theposition of the loading port SP on the track 2. The destination point Pis a position where a load L is able to be loaded (carried) from theloading port SP, and is a position around or a position adjacent to orin a vicinity of the loading port SP. The destination point P is atarget position of traveling in response to the transport command. Thetransport command includes a command to cause the traveling vehicle 3 toload a load L thereon at the loading port SP. The traveling vehiclecontroller 4 assigns the transport command to an empty traveling vehicle3E of a plurality of traveling vehicles 3 (described below). The emptytraveling vehicle 3E is a traveling vehicle 3 to which a transportcommand has not been assigned, including a traveling vehicle 3 that isempty without a load L being conveyed.

The traveling vehicle controller 4 is configured or programmed toinclude an input 41, a display 42, a communicator 43, and a commandassignment controller 44. The input 41 is, for example, a keyboard and amouse and to which various operations and various set values are inputby a user. The display 42, for example, includes a liquid crystaldisplay and displays, for example, a screen for various settings anddisplay a screen for inputs input with the input 41. The communicator 43is a processing device that communicates with another device, forexample. The communicator 43, for example, transmits a transport commandto a traveling vehicle 3 and receives traveling information of thetraveling vehicle 3 via a wireless communication network.

The command assignment controller 44 is, for example, an electroniccontroller including a CPU, a ROM, and a RAM. The command assignmentcontroller 44 may be implemented by, for example, software defined by aprogram that is able to be stored in the ROM and loaded into the RAM tobe executed by the CPU. Herein, the command assignment controller 44 maybe implemented by hardware, for example, an electronic circuit.

The command assignment controller 44 detects a first-to-arrive emptytraveling vehicle (first-to-arrive traveling vehicle, hereinafter,simply called “first-to-arrive empty traveling vehicle”) that is able toreach the destination point P first among a plurality of empty travelingvehicles 3E based on a plurality of travel route candidates on which theempty traveling vehicles 3E travel along the track 2 from the respectivepositions thereof to reach the destination point P. Specifically, thecommand assignment controller 44 detects the first-to-arrive emptytraveling vehicle based on the respective total costs of the travelroute candidates. The command assignment controller 44 calculates thetotal costs of the respective travel route candidates, and detects asthe first-to-arrive empty traveling vehicle an empty traveling vehicle3E corresponding to a travel route candidate the total cost of which isthe lowest. The command assignment controller 44 assigns a transportcommand to the first-to-arrive empty traveling vehicle thus detected.

Each travel route candidate is a candidate of the locus of an emptytraveling vehicle 3E to travel, which is set between the position of theempty traveling vehicle 3E and the destination point P on the track 2.The total cost is a period of time for the traveling vehicle 3 to travelon the travel route candidate. The total cost is able to be determinedbased on a route distance that is a distance along an itinerary (locus)of the travel route candidate and the estimated vehicle speed of thetraveling vehicle 3. For the total cost, a period of time for a straightroute is shorter even if the route distance is long, and a period oftime for a curved route is longer even if the distance is short. Thetotal cost is a value determined by adding up a cost along the travelroute candidate. For sections (inter-point mark sections) that areseparated by the respective point marks attached to the track 2, thecost corresponds to a period of time for the traveling vehicle 3 totravel in each section. A cost is set (assigned) to each point mark inadvance. The total cost will be described below.

Herein, during detection of the first-to-arrive empty traveling vehicle,in a case when an empty traveling vehicle 3E traveling toward a branchpoint BP is located within a range of a branch-switching impossibledistance Z from the branch point BP and is scheduled to travel toward amain way at the branch point BP, the command assignment controller 44excludes from the travel route candidates a post-course-switch travelroute that is a travel route on which this empty traveling vehicle 3Eproceeds toward a branch way when passing through the branch point BPfirst after the moment of the case as a starting point (hereinafter,simply called “post-course-switch travel route”).

The branch-switching impossible distance Z corresponds to a distance toswitch the branch mechanism 33 from its current state in which thetraveling vehicle 3 is to branch off toward the main way or toward thebranch way at the branch point BP to a state in which the travelingvehicle 3 is to branch off toward the opposite branch way. Because thetraveling vehicle 3 switches the branch mechanism 33 while traveling onthe track 2, the branch-switching impossible distance Z is, in otherwords, a shortest travel distance to switch the branch mechanism 33 tothe state in which the traveling vehicle 3 is to branch off toward theopposite branch way while traveling. When the distance between thetraveling vehicle 3 and the branch point BP is shorter than thebranch-switching impossible distance Z, the traveling vehicle 3 is notable to switch the branch mechanism 33 to the state in which it is tobranch off toward the opposite branch way before reaching to the branchpoint BP. The branch-switching impossible distance Z is a threshold thatis set in advance and stored. The branch-switching impossible distance Zis set to increase continuously or stepwise as the vehicle speed of theempty traveling vehicle 3E increases. The branch-switching impossibledistance Z herein is set for each of a short distance, a middledistance, and a long distance based on the cases when the vehicle speedof the empty traveling vehicle 3E is low, middle, and high,respectively, as exemplified below, for example. The branch-switchingimpossible distance Z is able to be determined by tests, experiences, ora simulation, for example.

-   -   Low speed (lower than 1000 mm/s): Short distance    -   Middle speed (equal or substantially equal to or higher than        1000 mm/s and lower than 2000 mm): Middle distance    -   High speed (higher than 2000 mm/s): Long distance

The position of the empty traveling vehicle 3E that is a criterion todetermine whether it is located within the range of the branch-switchingimpossible distance Z is not limited to a particular one, and may be aposition of the reader of the position determiner 31 in the emptytraveling vehicle 3E, or may be a central position (position of thecenter of gravity), a front-end position, or a rear-end position of theempty traveling vehicle 3E. The position of the branch point BP as astarting point of the branch-switching impossible distance Z is notlimited to a particular one, and may be set with respect to a point ofintersection of the respective central lines of the main way and thebranch way, or may be set with respect to any point in an area to branchon the track 2.

The command assignment controller 44 as described above performsspecifically pseudo-shift processing and inverse route search processing(search processing). The following describes the pseudo-shift processingand the inverse route search processing.

As shown in FIG. 3 and FIG. 4, when an empty traveling vehicle 3Etraveling toward a branch point BP on the track 2 is located within arange of a branch-switching impossible distance Z from the branch pointBP and is scheduled to travel toward the main way at the branch pointBP, the pseudo-shift processing determines, during detection of thefirst-to-arrive empty vehicle, that the empty traveling vehicle 3E islocated at a position downstream of the branch point BP and on the sideof the main way. Specifically, when the remaining distance for the emptytraveling vehicle 3E up to the branch point BP is shorter than thebranch-switching impossible distance Z, the pseudo-shift processingvirtually shifts the position of the empty traveling vehicle 3Erecognized by the traveling vehicle controller 4 from upstream of thebranch point BP to downstream thereof on the travel schedule route ofthe empty traveling vehicle 3E. In other words, the pseudo-shiftprocessing shifts the position (actual position) of the empty travelingvehicle 3E that is approaching to a distance equal or substantiallyequal to or shorter than the branch-switching impossible distance Z fromthe branch point BP to a position (pseudo-position) on the side of themain way that is downstream of the branch point BP and on which theempty traveling vehicle 3E is scheduled to travel in recognition of thetraveling vehicle controller 4.

The example shown in FIG. 3 and FIG. 4 is an example in which an emptytraveling vehicle 3E proceeds straight at a branch point BP (proceedstoward the loop travel path 2A at the branch point BP). In this example,the pseudo-shift processing fictitiously determines the position of theempty traveling vehicle 3E that is traveling upstream of the branchpoint BP on the track 2 and within the range of the branch-switchingimpossible distance Z as a position on the loop travel path 2A on theside of proceeding straight downstream of the branch point BP.

As shown in FIG. 4, the pseudo-shift processing determines that theempty traveling vehicle 3E is located downstream of the branch point BPand within a distance range K equal or substantially equal to or shorterthan the vehicle length of the empty traveling vehicle 3E from thebranch point BP. In other words, the pseudo-shift processing causes theposition of the empty traveling vehicle 3E to jump from upstream of thebranch point BP to downstream thereof, and the landing spot is set to beimmediately ahead of the branch point BP. For example, the position of apoint mark attached immediately downstream of the branch point BP on thetrack 2 is located apart from the branch point BP by a distance equal orsubstantially equal to or shorter than the vehicle length of the emptytraveling vehicle 3E, and thus the pseudo-shift processing sets theposition of this point mark as a pseudo-position. The pseudo-shiftprocessing is periodically performed. Herein, the pseudo-shiftprocessing is performed every time when new traveling information isreceived.

As one example, in the pseudo-shift processing, a series of processesshown in FIG. 5 is periodically and repeatedly performed for each of thetraveling vehicles 3. Specifically, to begin with, traveling informationis acquired from each traveling vehicle 3 (step S1). Based on thetraveling information, whether the traveling vehicle 3 is an emptytraveling vehicle 3E and is traveling is determined (step S2). If YES atstep S2 above, based on the traveling information, whether the emptytraveling vehicle 3E is located upstream of a branch point BP and withina range of a branch-switching impossible distance Z is determined (stepS3).

If YES at step S3 above, the position of the empty traveling vehicle 3Einternally recognized by the traveling vehicle controller 4 isfictitiously shifted from the actual position (position upstream of thebranch point BP) based on the traveling information to a pseudo-position(pseudo-position downstream of the branch point BP and on the side of amain way for which the empty traveling vehicle 3E is heading) (step S4).If NO at step S2 above, if NO at step S3 above, or after step S4 above,the series of processes in this period is completed, and then step S1above is performed again in the next period.

By the pseudo-shift processing described above, when the travelingvehicle controller 4 has recognized that the empty traveling vehicle 3Eis located in the pseudo-position, a post-course-switch travel route isnot searched for in the inverse route search processing described later,that is, the post-course-switch travel route is excluded from aplurality of travel route candidates that are provided as referencesduring detection of the first-to-arrive empty traveling vehicle.

The inverse route search processing searches for a shortest travel routecandidate that is a travel route candidate the total cost of which issmallest, and detects as a first-to-arrive empty traveling vehicle anempty traveling vehicle 3E corresponding to the shortest travel routecandidate thus searched for. The shortest travel route candidate is atravel route candidate that provides the quickest arrival at thedestination point P. The inverse route search processing is performedwhen the traveling vehicle controller 4 has generated a transportcommand.

Specifically, the inverse route search processing includes first tofifth processes. The first process examines routes on the track 2 totrace them from the destination point P in a direction opposite to thetraveling direction of each empty traveling vehicle 3E, therebysearching for a travel route candidate. The second process sets thetravel route candidate searched for in the first process as a shortesttravel route candidate, and also sets the total cost of this travelroute candidate as a minimum cost (shortest period of time). The thirdprocess examines routes on the track 2 to trace them from thedestination point P in a direction opposite to the traveling directionof each empty traveling vehicle 3E, thereby searching for a travel routecandidate the total cost of which is smaller than the minimum cost. Thefourth process sets the travel route candidate searched for in the thirdprocess as a shortest travel route candidate, and also sets the totalcost of this travel route candidate as a minimum cost, and then returnsto the third process. If a travel route candidate is not able to besearched for in the third process and unexamined routes have becomedepleted on the track 2, the fifth process ends the processing.

As one example, in the inverse route search processing, a series ofprocesses shown in FIG. 6 is performed when the traveling vehiclecontroller 4 has generated a transport command. Specifically, to beginwith, the positions of a plurality of empty traveling vehicles 3E andthe position of the destination point P in the generated transportcommand are recognized (step S11). A travel route candidate is searchedfor, the travel route candidate searched for is set as a shortest travelroute candidate, and also the total cost of this travel route candidateis set as a minimum cost to be stored in the traveling vehiclecontroller 4 (step S12).

A travel route candidate the total cost of which is smaller than theminimum cost on the track 2 is searched for (step S13). Whether thesearching at step S13 above has succeeded and a new travel routecandidate the total cost of which is smaller than the minimum cost hasbeen found is determined (step S14). If YES at step S14 above, thetravel route candidate that has been searched for is set as a shortesttravel route candidate and also the total cost of this travel routecandidate is set as a minimum cost to be stored (overwritten) in thetraveling vehicle controller 4 (step S15). Subsequently, the processingreturns to the process of step S13 above.

If NO at step S14 above, whether unexamined routes have become depletedon the track 2 is determined (step S16). If NO at step S16 above, theprocessing returns to the process of step S13 above. If YES at step S16above, the empty traveling vehicle 3E of the shortest travel routecandidate is detected as a first-to-arrive empty traveling vehicle, andthe inverse route search processing ends (step S17).

FIGS. 7A and 7B to FIG. 11 are diagrams showing features of the inverseroute search processing. In the following description, an example ofanother track layout is provided that is different from the track layoutof FIG. 1 for convenience in description. In the example of the tracklayout shown in FIGS. 7A and 7B to FIG. 11, the track 2 is depicted witha plurality of point marks I1 to I23 attached to the track 2 and linksbetween the point marks I1 to I23. A destination point P of a transportcommand corresponds to the position of the point mark I8. An emptytraveling vehicle 3E is in a position corresponding to the point markI2.

In the traveling vehicle controller 4, cost tables set in advance forthe respective point marks I1 to I23 are stored. In each cost table, acost is set for each point mark to be traced in examination. Forexample, the cost table for the point mark I4 includes information inwhich the cost of examination tracing the point mark I5 is 1, the costof examination tracing the point mark I11 is 2, and the cost ofexamination tracing the point mark I3 is 1. The cost tables are able tobe constructed by tests, experiences, or a simulation, for example. Thecost tables are able to be constructed based on, for example, lengthsand shapes of links that are connected to the corresponding point marks.

As shown in FIG. 7A, to begin with, routes are examined to be tracedfrom the point mark I8 corresponding to the destination point P in adirection opposite to the traveling direction of the empty travelingvehicle 3E to prepare a route table R0. In the route table R0, asexpressed by Formula (1) below, the point marks I8, I7, I6 that arealigned in the order of tracing in the examination are set as routedata.R0=I8,I7,I6  (1)

Costs are added up by referring to the cost tables of the respectivepoint marks I8, I7, I6 traced in the route examination to calculate thetotal cost of the route table R0. For example, the cost of routeexamination tracing the point mark I7 is 1 in the cost table for thepoint mark I8, and the cost of route examination tracing the point markI6 is 1 in the cost table for the point mark I7, and thus the total costof the route table R0 herein is 2.

Subsequently, because the point mark I6 corresponds to a merging point(branch point in the inverse route search processing) of the track 2, aroute table R1 is newly prepared, and the route tables R0, R1 ofFormulas (2), (3) below are set. Costs are added up for the respectiveroute tables R0, R1 to calculate the total costs of the route tables R0,R1.R0=I8,I7,I6,I5  (2)R1=I8,I7,I6,I23  (3)

As shown in FIG. 7B, for the route table R0, the route examination iscontinued, and also costs are added up to calculate the total cost.Consequently, the empty traveling vehicle 3E is found at the position ofthe point mark I2, and the route table R0 of Formula (4) below issearched for as information of the shortest travel route candidate, andthus the route examination of the route table R0 is completed. The totalcost of the route table R0 is stored as the minimum cost.R0=I8,I7,I6,I5,I4,I3,I2  (4)

Herein, in order to reduce the amount of route data, point marks set inthe route tables may be limited to point marks that correspond to any ofthe destination point P, the branch point BP, and the empty travelingvehicle 3E. Thus, Formula (4) above may be rewritten as Formula (5)below. Hereinafter, similar features apply to other route tables.R0=I8,I4,I3,I2  (5)

As shown in FIG. 8A, for the route table R1, the route examination iscontinued, and also costs are added up to calculate the total cost.Thus, the route table R1 of Formula (6) below is set.R1=I8,I23,I22,I21,I20,I19,I18  (6)

Subsequently, because the point mark I18 corresponds to a merging pointof the track 2, a route table R2 is newly prepared, and the route tablesR1, R2 of Formulas (7), (8) below are set. Costs are added up for therespective route tables R1, R2 to calculate the total costs of the routetables R1, R2.R1=I8,I23,I22,I21,I20,I19,I18,I17  (7)R2=I8,I23,I22,I21,I20,I19,I18,I24  (8)

As shown in FIG. 8B, for the route table R1, the route examination iscontinued, and also costs are added up to calculate the total cost.Thus, the route table R1 of Formula (9) below is set.R1=I8,I23,I13,I12,I11  (9)

Subsequently, because the point mark I11 corresponds to a merging pointof the track 2, a route table R3 is newly prepared, and thus the routetables R1, R3 of Formulas (10), (11) below are set. Costs are added upfor the respective route tables R1, R3 to calculate the total costs ofthe route tables R1, R3.R1=I8,I23,I13,I12,I11,I4  (10)R3=I8,I23,I13,I12,I11,I10  (11)

As shown in FIG. 9A, for the route table R1, the route examination iscontinued, and also costs are added up to calculate the total cost.Thus, the route table R1 of Formula (12) is set. Consequently, the emptytraveling vehicle 3E is found at the position of the point mark I2, andthe route examination of the route table R1 is completed. If the totalcost of the route table R1 is smaller than the minimum cost that iscurrently stored, the route table R1 of Formula (12) below is searchedfor as information of the shortest travel route candidate, and also thecurrently stored one is overwritten with the total cost of the routetable R1 as the minimum cost. However, in route examination in the routetable R1, at the time when the total cost has exceeded the minimum cost,further examination is not necessary, and thus the examination may bestopped (similar features apply to the other route examination).R1=I8,I23,I13,I4,I3,I2  (12)

As shown in FIG. 9B, for the route table R2, the route examination iscontinued, and also costs are added up to calculate the total cost.Thus, the route table R2 of Formula (13) below is set.R2=I8,I23,I13,I12,I11  (13)

Subsequently, because the point mark I11 corresponds to a merging pointof the track 2, a route table R4 is newly prepared, and the route tablesR2, R4 of Formulas below (14), (15) are set. Costs are added up for therespective route tables R2, R4 to calculate the total costs of the routetables R2, R4.R2=I8,I23,I13,I12,I11,I4  (14)R4=I8,I23,I13,I12,I11,I10  (15)

As shown in FIG. 10A, for the route table R2, the route examination iscontinued, and also costs are added up to calculate the total cost.Thus, the route table R2 of Formula (16) below is set. Consequently, theempty traveling vehicle 3E is found at the position of the point markI2, and the route examination of the route table R2 is completed. If thetotal cost of the route table R2 is smaller than the minimum cost thatis currently stored, the route table R2 of Formula (16) below issearched for as information of the shortest travel route candidate, andalso the currently stored one is overwritten with the total cost of theroute table R2 as the minimum cost.R2=I8,I23,I13,I4,I3,I2  (16)

As shown in FIG. 10B, for the route table R3, the route examination iscontinued, and also costs are added up to calculate the total cost.Thus, the route table R3 of Formula (17) below is set. Because the routetable R3 includes the point mark I23 two times (i.e., includes a pointmark that has been already traced), it is determined at this point oftime further examination is not necessary, and the examination isstopped.R3=I8,I23,I13,I12,I11,I10,I23  (17)

As shown in FIG. 11, for the route table R4, the route examination iscontinued, and also costs are added up to calculate the total cost.Thus, the route table R4 of Formula (18) below is set. Because the routetable R4 includes the point mark I23 two times (i.e., includes a pointmark that has been already traced), it is determined at this point oftime that further examination is not necessary, and the examination isstopped. Subsequently, because unexamined routes have become depleted onthe track 2, the empty traveling vehicle 3E of the shortest travel routecandidate is set as a first-to-arrive empty traveling vehicle, and theinverse route search processing is completed.R4=I8,I23,I13,I12,I11,I10,I23  (18)

As described above, in the inverse route search processing, thefollowing condition to allow search, the following condition to stop thesearch, and the following condition to end the search are set, and underthese conditions, routes are to be examined.

Condition to allow searching:

-   -   when an empty traveling vehicle 3E has been found and the total        cost is smaller than the minimum cost

Condition to stop searching:

-   -   when returning to the point mark of a destination point P for        which examination has been started    -   when returning to the point mark of a branch point BP that has        been already traced    -   when the total cost exceeds the minimum cost

Condition to end searching:

-   -   when unexamined routes have become depleted

As described above, in the traveling vehicle controller 4 and thetraveling vehicle system 1, if the distance from a branch point BP tothe position of an empty traveling vehicle 3E that is traveling is equalor substantially equal to or shorter than the branch-switchingimpossible distance Z, the branch mechanism is not able to be switchedbefore the branch point BP is reached. Thus, it is determined that thisempty traveling vehicle 3E is not able to change at the branch point BPthe course direction into which it is scheduled to proceed (the emptytraveling vehicle 3E has to proceed at the branch point BP in the coursedirection in which it is scheduled to proceed), and thepost-course-switch travel route is excluded from a plurality of travelroute candidates that are provided as references during detection of thefirst-to-arrive empty traveling vehicle. Thus, a situation in which theempty traveling vehicle 3E to which the transport command has beenassigned is not able to change courses at the branch point BP anddetours to travel to the destination point P is able to be avoided.

Consequently, in the example of the track layout shown in FIG. 1, thetransport command is able to be assigned to, instead of the emptytraveling vehicle 3E that has to proceed to the destination point Pafter traveling one round on the loop travel path 2A, the emptytraveling vehicle 3E that is able to reach the destination point P inthe shortest time on the loop travel path 2B. The traveling vehiclecontroller 4 is able to improve the method of selecting a travelingvehicle when assigning the transport command to the optimum emptytraveling vehicle 3E. With respect to whether an empty traveling vehicle3E is able to proceed toward the destination point P at a branch pointBP and based on the positional relation between the empty travelingvehicle 3E and the destination point P, the transport command is able tobe assigned to an empty traveling vehicle 3E that is able to reach thedestination point P first. Accordingly, an empty traveling vehicle 3E isable to quickly reach the destination point P.

In the traveling vehicle controller 4 and the traveling vehicle system1, when an empty traveling vehicle 3E traveling toward a branch point BPon the track 2 is located within a range of a branch-switchingimpossible distance Z from the branch point BP and is scheduled toproceed toward a main way at the branch point BP, the pseudo-shiftprocessing is performed. By the pseudo-shift processing, this emptytraveling vehicle 3E is able to be determined to be located downstreamof the branch point BP and on the side of the main way. Thus, thepost-course-switch travel route is excluded from the travel routecandidates. Thus, a situation in which the empty traveling vehicle 3E towhich the transport command has been assigned is not able to changecourses at the branch point BP and detours to travel to the destinationpoint P is able to be avoided.

The traveling vehicle controller 4 and the traveling vehicle system 1perform the inverse route search processing of searching for a shortesttravel route candidate that is a travel route candidate the total costof which is smallest and detecting as a first-to-arrive empty travelingvehicle an empty traveling vehicle 3E corresponding to the shortesttravel route candidate thus searched for. Thus, the first-to-arriveempty traveling vehicle is able to be accurately detected.

If the distance between the pseudo-position of an empty travelingvehicle 3E subjected to the pseudo-shift processing and the actualposition thereof is longer, another empty traveling vehicle 3E is morelikely to exist therebetween. In this case, even though the other emptytraveling vehicle 3E is able to reach the destination point P first, theempty traveling vehicle 3E subjected to the pseudo-shift processing hasbeen recognized to be located in the pseudo-position, and thus there isa possibility that the command is assigned to the empty travelingvehicle 3E subjected to the pseudo-shift processing. Accordingly, in thepseudo-shift processing of the traveling vehicle controller 4 and thetraveling vehicle system 1, the empty traveling vehicle 3E is determinedto be located downstream of the branch point BP and within the distancerange K equal or substantially equal to or shorter than the vehiclelength of the empty traveling vehicle 3E from the branch point BP. Thiseliminates the possibility that another empty traveling vehicle 3Eexists between the pseudo-position of the empty traveling vehicle 3Esubjected to the pseudo-shift processing and the actual positionthereof. Accordingly, a situation in which the transport command isassigned to the empty traveling vehicle 3E subjected to the pseudo-shiftprocessing is able to be avoided, because the pseudo-shift processinghas been performed thereon although the transport command should beoriginally assigned to the other empty traveling vehicle 3E.

In order to reliably change courses of an empty traveling vehicle 3E ata branch point BP, the branch-switching impossible distance Z beingupstream from the branch point BP tends to increase as the vehicle speedof the empty traveling vehicle 3E increases. Accordingly, in thetraveling vehicle controller 4 and the traveling vehicle system 1, thebranch-switching impossible distance Z is set to increase continuouslyor stepwise as the vehicle speed of the empty traveling vehicle 3Eincreases. Thus, the branch-switching impossible distance Z is able tobe set according to this tendency.

In the traveling vehicle controller 4 and the traveling vehicle system1, the inverse route search processing includes: the first process ofexamining routes on the track 2 to trace them from the destination pointP in a direction opposite to the traveling direction of each emptytraveling vehicle 3E, thereby searching for a travel route candidate;the second process of setting the travel route candidate searched for inthe first process as a shortest travel route candidate, and also settingthe total cost of this travel route candidates as a minimum cost; thethird process of examining routes on the track 2 to trace them from thedestination point P in a direction opposite to the traveling directionof each empty traveling vehicle 3E, thereby searching for a travel routecandidate the total cost of which is smaller than the minimum cost; thefourth process of setting the travel route candidate searched for in thethird process as a shortest travel route candidate, and also setting thetotal cost of this travel route candidate as a minimum cost, and thenreturning to the third process; and the fifth process of ending theprocessing if a travel route candidate is not able to be searched for inthe third process and unexamined routes have become depleted on thetrack 2. Thus, the inverse route search processing is able to bespecifically and effectively performed.

Although preferred embodiments of the present invention have beendescribed above, the present invention is not limited to the preferredembodiments described above, and various modifications may beimplemented within a scope of the present invention.

In the above-described preferred embodiments, when the pseudo-shiftprocessing is performed, the command assignment controller 44 may add acorrection cost corresponding to the period of time for an emptytraveling vehicle 3E subjected to the pseudo-shift processing to travelbetween the pseudo-position of the empty traveling vehicle 3E and theactual position thereof to the total cost of the route table of theempty traveling vehicle 3E in the inverse route search processing (theperiod of time calculated for the travel route candidate correspondingto the empty traveling vehicle 3E).

For example, as shown in FIG. 12, in the inverse route searchprocessing, if YES at step S14 above, whether the empty travelingvehicle 3E of the travel route candidate search for is subjected to thepseudo-shift processing is determined (step S21). If NO at step S21above, the travel route candidate searched for is set as the shortesttravel route candidate, and also the total cost of this travel routecandidate is set as the minimum cost to be stored in the travelingvehicle controller 4 (step S22). Subsequently, the processing returns tothe process of step S13 above.

If YES at step S21 above, whether a value determined by adding thecorrection cost to the total cost of the travel route candidate searchedfor is smaller than the minimum cost is determined (step S23). If YES atstep S23 above, the travel route candidate searched for is set as theshortest travel route candidate, and the value determined by adding thecorrection cost to the total cost of this travel route candidates is setas the minimum cost to be stored in the traveling vehicle controller 4(step S24). Subsequently, the processing returns to the process of stepS13 above. If NO at step S23 above, the processing returns to theprocess of step S13 above. Herein, the correction cost may be calculatedwhen the pseudo-shift processing is performed, and may be stored in thetraveling vehicle controller 4.

By this addition of the correction cost, the total cost of the routetable of the empty traveling vehicle 3E subjected to the pseudo-shiftprocessing is able to be corrected. Accordingly, while determining thatthe empty traveling vehicle 3E is located downstream of the branch pointBP, the total cost in the inverse route search processing is able to becalculated based on the positional relation between the actual positionof the empty traveling vehicle 3E and the destination point P.

In the above-described preferred embodiments, the traveling vehiclecontroller 4 performs the pseudo-shift processing, thus consequentlyexcluding the post-course-switch travel route from the travel routecandidates that are provided as references during detection of thefirst-to-arrive empty traveling vehicle. However, the present inventionis not limited to this specific implementation. The traveling vehiclecontroller 4 may, without performing the pseudo-shift processing,estimate routes based on traveling information of the empty travelingvehicles 3E and directly exclude the post-course-switch travel routefrom the travel route candidates that are provided as references duringdetection of the first-to-arrive empty traveling vehicle. For example,based on the actual position, the vehicle speed, and the travel scheduleroute of each empty traveling vehicle 3E, route examination in theinverse route search processing may be performed with a route tablecorresponding to the post-course-switch travel route being excluded.

Although costs or total costs are included in the above-describedpreferred embodiments, the present invention is not limited to thisspecific implementation. For example, route distances may be included.Other various parameters may be included to define a period of time foreach traveling vehicle 3 to travel.

Track layouts in the above-described preferred embodiments are notlimited to the examples in FIG. 1, and FIGS. 7A and 7B to FIG. 11, andvarious track layouts may be provided. The preferred embodimentsdescribed above has been described in which the traveling vehicles 3 areoverhead traveling vehicles as one example. However, other examples ofthe traveling vehicles include automated guided traveling vehicles andstacker cranes that travel on a track installed on the ground orabutments.

In the above-described preferred embodiments, in the inverse routesearch processing, when routes are examined to be traced from thedestination point P on the track 2 in a direction opposite to thetraveling direction, when an empty traveling vehicle 3E has been foundfor the first time (in the case of the first finding of the emptytraveling vehicle 3E), and if this empty traveling vehicle 3E istraveling toward a branch point BP on the track 2, is located within therange of the branch-switching impossible distance Z from the branchpoint BP, and is scheduled to proceed toward the main way at the branchpoint BP, this finding may be ignored. By this process, thepost-course-switch travel route is excluded from the travel routecandidates, and thus a situation in which the empty traveling vehicle 3Eto which the transport command is assigned detours to travel to thedestination point P is able to be avoided, and an empty travelingvehicle 3E is able to be controlled to quickly reach the destinationpoint P.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

The invention claimed is:
 1. A traveling vehicle controller to assign,to any one of a plurality of traveling vehicles that each travels on atravel path including a branch point, a command to travel to adestination point on the travel path, the traveling vehicle controllercomprising: a command assignment controller configured or programmed todetect a first-to-arrive traveling vehicle that is able to reach thedestination point first among the plurality of traveling vehicles, basedon travel route candidates on which the plurality of traveling vehiclestravel along the travel path from respective positions to reach thedestination point, and to assign the command to the first-to-arrivetraveling vehicle to cause the first-to-arrive traveling vehicle totravel to the destination point based on the command; wherein duringdetection of the first-to-arrive traveling vehicle, when one of theplurality of traveling vehicles traveling toward the branch point on thetravel path is located within a range of a branch-switching impossibledistance from the branch point, which corresponds to a shortest distancefrom the branch point at which the one of the plurality of travelingvehicles is able to switch course, and is scheduled to proceed toward amain way at the branch point, the command assignment controller isconfigured or programmed to perform pseudo-shift processing by which anactual position of the one of the plurality of traveling vehiclesupstream of the branch point is determined to be virtually located in apseudo-position downstream of the branch point and on a side of the mainway.
 2. The traveling vehicle controller according to claim 1, whereinthe command assignment controller is configured or programmed to:calculate, for each of the travel route candidates, a period of time foreach of the plurality of traveling vehicles to travel thereon; anddetect, as the first-to-arrive traveling vehicle, a traveling vehiclecorresponding to a travel route candidate on which the period of time isshortest.
 3. The traveling vehicle controller according to claim 2,wherein, after performing the pseudo-shift processing, the commandassignment controller is configured or programmed to add a period oftime to travel between the pseudo-position of the one of the pluralityof traveling vehicles subjected to the pseudo-shift processing and theactual position of the one of the plurality of traveling vehicles to theperiod of time calculated for the travel route candidate correspondingto the traveling vehicle.
 4. The traveling vehicle controllercorresponding to claim 1, wherein, in the pseudo-shift processing, thecommand assignment controller is configured or programmed to determinethe one of the plurality of traveling vehicles to be located downstreamof the branch point and within a distance range equal or substantiallyequal to or shorter than a vehicle length of the one of the plurality ofraveling vehicles from the branch point.
 5. The traveling vehiclecontroller according to claim 1, wherein the branch-switching impossibledistance is set to increase continuously or stepwise as a vehicle speedof the one of the plurality of traveling vehicles increases.
 6. Atraveling vehicle controller to assign, to any one of a plurality oftraveling vehicles that each travels on a travel path including a branchpoint, a command to travel to a destination point on the travel path,the traveling vehicle controller comprising: a command assignmentcontroller configured or programmed to detect a first-to-arrivetraveling vehicle that is able to reach the destination point firstamong the plurality of traveling vehicles, based on travel routecandidates on which the plurality of traveling vehicles travel along thetravel path from respective positions to reach the destination point,and to assign the command to the first-to-arrive traveling vehicle tocause the first-to-arrive traveling vehicle to travel to the destinationpoint based on the command; wherein during detection of thefirst-to-arrive traveling vehicle, in a case when one of the pluralityof traveling vehicles traveling toward the branch point on the travelpath is located within a range of a branch-switching impossible distancefrom the branch point, which corresponds to a shortest distance from thebranch point at which the one of the plurality of traveling vehicles isable to switch course, and is scheduled to travel toward a main way atthe branch point, the command assignment controller is configured orprogrammed to exclude, from the travel route candidates, apost-course-switch travel route on which the one of the plurality oftraveling vehicles proceeds toward a branch way when passing through thebranch point first after the moment of the case as a starting point. 7.A traveling vehicle system comprising: a travel path including a branchpoint; a plurality of traveling vehicles that each travels along thetravel path; and the traveling vehicle controller according to claim 1.8. The traveling vehicle controller according to claim 2, wherein thebranch-switching impossible distance is set to increase continuously orstepwise as a vehicle speed of the one of the plurality of travelingvehicles increases.
 9. The traveling vehicle controller according toclaim 3, wherein the branch-switching impossible distance is set toincrease continuously or stepwise as a vehicle speed of the one of theplurality of traveling vehicles increases.
 10. The traveling vehiclecontroller according to claim 4, wherein the branch-switching impossibledistance is set to increase continuously or stepwise as a vehicle speedof the one of the plurality of traveling vehicles increases.